Atypical clinical manifestations of a fatal case of generalized meningococcal infection caused by Neisseria meningitidis serogroup W, part of the clonal complex cc11

The proportion of invasive meningococcal disease (IMD) caused by Neisseria meningitidis serogroup W (NmW) has increase in recent years. NmW contribute the largest mortality ratio (up to 29%) compared to other serogroups. IMD caused by NmW with the sequence type ST‑11 has been associated with multiple causes of epidemiological problems abroad, are of particular epidemiological concern. The aim of the study was to describe a fatal case of IMD caused by NmW with an analysis of the antigenic and genetic pathogen’s features. Materials and methods . The description of clinical manifestations was taken from the GMI registration report form received by the Reference Center for Monitoring Bacterial Meningitis. The microbiological and molecular biological methods for the pathogen investigation were performed by generally accepted once using the plugins and information of the PubMLST database. Results and discussion . The clinical manifestations of IMD fatal case with a diagnosis of «acute gastroenterocolitis, grade II hypovolemic shock» was described. The IMD was caused by NmW extracted from the cerebrospinal fluid. Pathogen typing detects the previously undescribed sequence type ST‑18929 from the ST‑11 complex (cc11), and the antigenic profile characteristic of this clonal complex, W: P1.5,2: F1–1. Whole genome analysis of the pathogen demonstrated minor differences from the cc11 clonal complex strains circulating in Moscow in 2013–2020. Conclusion. The described case is a striking example of the atypical clinics of IMD caused by the NmW. The most genetically similar IMD pathogens of W serogroup have been repeatedly isolated in Moscow in previous years, which does not allow us to speak with confidence about the import of increased virulence pathogens into Russia.